Perhaps the highlight of the announcement today was that the company will be releasing its Roslyn compiler stack as open source under the Apache 2.0 license. Roslyn includes a C# and Visual Basic.NET compiler, offering what Microsoft calls a "compiler as a service".

This is more than just a code dump - Microsoft is launching the .NET Foundation, with representatives from Microsoft, GitHub, and Xamarin, among others, to act as stewards for the various related open source projects.